Fuel efficiency has traditionally been an important performance criterion for vehicles. As gas prices continue to rise and emissions regulations grow more stringent, vehicular fuel efficiency become even more critical. The transportation industry is particularly cognizant of this criterion due to the correlation between fuel efficiency and a company's bottom line. This is particularly true with respect to the trucking industry.
According to the U. S. Department of Energy (DOE), Class 8 trucks haul approximately 69% of all freight tonnage and use more than 20% of the fuel consumed in the United States. Trucks having a gross vehicle weight rating (GVWR) above 33,000 pounds qualify as Class 8. Hence, there is a need to reduce the fuel consumption of trucks, and particularly of large, long haul trucks.
In 2020, the Department of Energy (DOE) initiated a ‘SuperTruck’ program to challenge engine and vehicle manufacturers to create a 50% more efficient Class 8 truck. The goal of this five-year program is to design a heavy-duty Class 8 truck which demonstrates a 50% improvement in overall freight efficiency measured in ton-miles per gallon. To ensure there is total vehicle improvement, 30% of the efficiency must come from the tractor and trailer, while the remaining 20% must come from the engine. Each vehicle's engine also needs to show 50% brake thermal efficiency, and a path to achieve 55% brake thermal efficiency must be provided. Conventional approaches to achieving such efficiencies typically include improving engine performance, reducing vehicular weight, and reducing aerodynamic drag.